Generally, a vehicle having an internal combustion engine mounted therein is provided with a catalyst device to purify exhaust gas. The catalyst device does not exhibit its effect unless it is heated to some extent, and accordingly, it is disposed near the internal combustion engine so that it is heated immediately.
However, immediately after the internal combustion engine has just started, i.e., when the catalyst device is still not warm, its purification effect is insufficient. Accordingly, using electric power to warm the catalyst device before starting the internal combustion engine, is considered. Such a catalyst device is also referred to as an electrically heated catalyst (EHC).
Japanese Patent Laying-Open No. 2000-220442 (PTD 1) discloses a vehicle having an EHC mounted therein.